Percussion Lock Repair 1842 Springfield

[Limestone]

Hello, looking for some advice. I am working on an original 1842 lock plate. I have a broken bridle, the alignment pin broke off in the lock plate. Which caused the upper bridle screw to shear off in the lock plate. I have removed the broken alignment pin and remainder of the screw. I purchased a new repro bridle. Placed it on the tumbler pin, appears to be the correct bridle. When I try to install the 2 bridle screws they go into the lock plate threads about half a turn. The screws will thread into the lock plate. My question is if I open up the 2 bridle screw holes a little with the next size drill bit or use a small round file will I create problems? Should I try harder to find an original bridle? Thanks in advance. Limestone

[P.W.Berkuta]

If it was mine I would open up the clearance holes in the bridle a SMALL amount until the screws fully thread into the plate.

[PAFlinter]

S&S has machined replacements and orginal bridles.  Dunno what kind you bought.  Here's the link
https://www.ssfirearms.com/proddetail.asp?prod=W15082&cat=82

[Limestone]

Thank you both for the reply.

[2 shots]

if you can see which way the screws have to go , you could file in that direction  rather than enlarging the entire hole.

[kutter]

Is the orig Bridle salvageable if you just replace the alignment pin in it? ,,and,, if that were the case, would that Bridle fit the lockplate screw pattern OK. Or would the 2 screws not quite line up then as well also and be a somewhat awkward fit with the Bridle in place..

If the orig is just cracked and still fits good,
I've Brazed and sometimes Hard Soldered (High  Temp Silver Solder) cracked Bridles in the past and they have held just fine. Perhaps the orig had be salvaged if it is a good fit on the plate.

[WKevinD]

I have a '42 Springfield lock that could be brought to fine condition, all parts are there if your interested.


Kevin

[Limestone]

Hello Kutter, I have the broken off alignment pin saved. Welding and brazing is not in my skill set right now. I need to do some research to see if the original  broken bridle is cast or machined. My guess is cast. I had thought about drilling the broken bridle pin area out and tapping and threading a new pin. Might make the bridle weak. Still thinking on it. Thanks for the reply

[Limestone]

2 shots, Thanks for the advice.

[Limestone]

Kevin, pm sent Thanks for the reply. Limestone

[Notchy Bob]

S&S has machined replacements and orginal bridles.  Dunno what kind you bought.  Here's the link
https://www.ssfirearms.com/proddetail.asp?prod=W15082&cat=82

Interchangeability among the Springfield locks is generally pretty good.  I recently worked on an 1864 Springfield lock which was missing the bridle.  I bought the machined replacement from S&S and it dropped right in... No slop, no drama.  I don't know for sure that it will fit an 1842 lock, but you could call and ask.

Notchy Bob

[Clark Badgett]

The screws are most likely not a current pitch in common usage. Don’t quote me, but for some reason 22 or 24 tpi comes to mind.

ETA: I looked up the thread pitches on US arms from 1795-1890. The US copied the French, even the metic sizes. (6mm X 1.5 pitch, 6 X 1.1, 6mm X 1, 5mm X .9, or 5mm X 1.) Also, it seems that the thread form was slightly different than modern.

[PAFlinter]

Just curious why you didn't just buy the orginal bridle I posted a link to?  Call them and he it on the way.  Easy, and done.

[Limestone]

PAFlinter, Clark Badgett and Notchy Bob, Thanks for the replies and reccomendations. So this is where I am at in the repair process. I tried contacting S&S phone and email. Not much luck right after the 4th most likely busy or taking some time off. I went to there web site and ordered a bridle and a set of new screws. It shipped yesterday should be here Thursday. Thanks for the help.